1. Enzymes
Unit 2

2. What is an enzyme?
An enzyme is a special protein +

3. What are they made of?
Enzymes are made of amino acids (just like proteins!!!)

4. The lock and key model Teacher notes
This four-stage animation demonstrates the principles of the ‘lock and key’ model. While showing the animation, the specific shape of the active site could be highlighted.
Suitable prompts could include:
What is special about the shape of the active site?
Is the enzyme the ‘lock’ or the ‘key’?

5. What do they do?
Enzymes start or speed up the rate of a chemical reaction.

6. How do they do that? Enzymes lower the activation energy
They make it easier for the reaction to start like lowering a hurdle
reaction (time)
energy (kJ)
Ea without enzyme
Ea with enzyme

7. What is a chemical reaction?
A chemical reaction is where atoms are rearranged into a different order
Reactants go into the reaction (left)
Products come out of the reaction (right)
Reactant 1 + Reactant 2 Product

8. How do they help with a chemical reaction?
Enzymes match up to a single partner like a lock and a key
We say they are specific + + ↔ ↔
enzyme
reactant +
enzyme-reactant complex ↔
products

9. What happens when they are done helping with the reaction?
After enzymes help start or speed up the chemical reaction they wait around to help with another reaction
We say they are reusable

10. What hurts enzymes?
Enzymes do not like changes in temperature.

11. What hurts enzymes?
Enzymes do not like changes in pH.

12. What happens to an enzyme when temperature or pH changes?
Enzymes denature (lose their shape, die) in extreme temperatures or pH.
denatured
normal
heat pH